Skolelinux looks promising, on its own little mini network.
The setup we have gone with is
-old pc running ipfire as gateway and dhcp. Yet to investigate DNS.
-newish goodish AMD processor and 4gb RAM (but standard sata drive) skolelinux combined server, workstation, thin client.
+later today I will get some y9s to build a bog standard workstation and add it to the network.
I have no reason to doubt that this will not work next week when I remove the main zentyal server from my current proper cs network, drop in skolelinux and wipe edubuntu from PCs and replace with skolelinux(debian)
When using raspberry pis on the network we will use standard pi user and just use sshfs to allow saving / accessing work.
Tested skolelinux standalone on an ancient "designed for windows xp" desktop. Lovely!
Edubuntu on the same desktop? Joke.
Useful tip for general administration of multiple user accounts here